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            <div><h5 class="title">
                <a name="asio.reference.basic_waitable_timer.cancel_one.overload2"></a><a class="link"
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                                                                                          title="basic_waitable_timer::cancel_one (2 of 2 overloads)">basic_waitable_timer::cancel_one
                (2 of 2 overloads)</a>
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    <p>
        (Deprecated: Use non-error_code overload.) Cancels one asynchronous operation
        that is waiting on the timer.
    </p>
    <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span
            class="identifier">size_t</span> <span class="identifier">cancel_one</span><span class="special">(</span>
    <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span> <span
                class="special">&amp;</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
    <p>
        This function forces the completion of one pending asynchronous wait
        operation against the timer. Handlers are cancelled in FIFO order. The
        handler for the cancelled operation will be invoked with the <code class="computeroutput"><span
            class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span
            class="special">::</span><span class="identifier">operation_aborted</span></code> error code.
    </p>
    <p>
        Cancelling the timer does not change the expiry time.
    </p>
    <h6>
        <a name="asio.reference.basic_waitable_timer.cancel_one.overload2.h0"></a>
        <span><a name="asio.reference.basic_waitable_timer.cancel_one.overload2.parameters"></a></span><a class="link"
                                                                                                          href="overload2.html#asio.reference.basic_waitable_timer.cancel_one.overload2.parameters">Parameters</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">ec</span></dt>
            <dd><p>
                Set to indicate what error occurred, if any.
            </p></dd>
        </dl>
    </div>
    <h6>
        <a name="asio.reference.basic_waitable_timer.cancel_one.overload2.h1"></a>
        <span><a name="asio.reference.basic_waitable_timer.cancel_one.overload2.return_value"></a></span><a class="link"
                                                                                                            href="overload2.html#asio.reference.basic_waitable_timer.cancel_one.overload2.return_value">Return
        Value</a>
    </h6>
    <p>
        The number of asynchronous operations that were cancelled. That is, either
        0 or 1.
    </p>
    <h6>
        <a name="asio.reference.basic_waitable_timer.cancel_one.overload2.h2"></a>
        <span><a name="asio.reference.basic_waitable_timer.cancel_one.overload2.remarks"></a></span><a class="link"
                                                                                                       href="overload2.html#asio.reference.basic_waitable_timer.cancel_one.overload2.remarks">Remarks</a>
    </h6>
    <p>
        If the timer has already expired when <code class="computeroutput"><span
            class="identifier">cancel_one</span><span class="special">()</span></code> is called, then the handlers for
        asynchronous
        wait operations will:
    </p>
    <div class="itemizedlist">
        <ul class="itemizedlist" type="disc">
            <li class="listitem">
                have already been invoked; or
            </li>
            <li class="listitem">
                have been queued for invocation in the near future.
            </li>
        </ul>
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    <p>
        These handlers can no longer be cancelled, and therefore are passed an
        error code that indicates the successful completion of the wait operation.
    </p>
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